Orientation and homing of the brush rabbit

Abstract:

A study of orientation and homing in brush rabbits, Sylvilagus
bachmani ubericolor (Miller), was conducted on the E. E. Wilson
Game Management Area 7 miles north of Corvallis, Oregon, between
July 1967 and April 1969. Sixty-seven individual rabbits were fitted
with radio-transmitters and returned to the field. Home ranges were
determined for 59 of these rabbits. Brush rabbits rarely left brushy
cover. The home ranges of males were larger than those of females
and the home ranges of juvenile males were larger than those of
adult males.
Nineteen of the 59 brush rabbits whose home ranges were determined
were displaced in 29 homing experiments. No rabbit was
displaced more than twice. Brush rabbits homed successfully in 15
of the 29 experiments. Brush rabbits did not "home" over distances
as great as those reported for other members of the genus or other
small mammals. Homing success was not inversely related to distance displaced as has been reported for other small mammals.
Rather, there was a distinct limit at about 600 feet beyond which no
rabbit homed. Random movements could not have accounted for the
high percentage of rabbits that homed. Therefore, it was concluded
that brush rabbit homing ability was characteristic of oriented movements.
Rabbits required as long as 36 days to complete a successful
homing experiment. A direct correlation was found between homing
time and distance displaced. This correlation was even higher when
the size of the rabbit's standard range was considered. It was concluded
that brush rabbit homing ability was related to the size of the
home range.
With one exception brush rabbits chose clear nights to "home"
indicating that sight was a primary mechanism involved in homing.
There was no correlation between season of the year and homing
ability, or between homing ability and sex or age. There was no
relationship between initial movements and compass direction or direction
of the home range. However, a significant number of rabbits
left the release box in the direction of the nearest cover. Brush
rabbits also restricted their routes of travel to brushy cover while
attempting to "home." Four factors were found which interfered
with homing: (1) inter-specific aggressive behavior, (2) roads, (3)
human and vehicular activity, and (4) predators. Brush rabbit home
ranges after first displacements were significantly smaller than original home ranges. However, home ranges after second displacements
were not smaller. The unusual movements of two rabbits are
discussed.